HYPERBILIRUBINEMIA AGGRAVATES RENAL ISCHEMIA REPERFUSION INJURY BY EXACERBATING PINK1-PARKIN-MEDIATED MITOPHAGY

Background: Hyperbilirubinemia is a common perioperative complication, which is associated with acute kidney injury. Bilirubin permeabilizes mitochondrial membranes leading to mitochondrial swelling and dysfunction. In this study, we aimed to determine the association between PINK1-PARKIN-mediated mitophagy and renal ischemia-reperfusion (IR) injury aggravated by hyperbilirubinemia. Methods: A C57BL/6 mouse hyperbilirubinemia model was induced via intraperitoneal injection of bilirubin solution. In addition, a hypoxia/reoxygenation (H/R) injury model of TCMK-1 cells was established. In these models, we determined the effects of hyperbilirubinemia on oxidative stress, apoptosis, mitochondrial damage, and fibrosis. Results: In vitro, colocalization of GFP-LC3 puncta and Mito-Tracker Red showed that the number of mitophagosomes increased in TCMK-1 cells under H/R and bilirubin condition. Silencing of PINK1 or inhibition of autophagy alleviated mitochondrial damage, oxidative stress, and apoptosis in H/R injury aggravated by bilirubin and decreased cell death detected by methyl-thiazolyl-tetrazolium. In vivo, hyperbilirubinemia increased serum creatinine level in the renal IR injury mice model. Hyperbilirubinemia enhanced apoptosis induced by renal IR. In addition, hyperbilirubinemia increased mitophagosomes and autophagosomes and disrupted mitochondrial cristae in the IR kidney. Inhibition of PINK1 or autophagy reduced histological damages by alleviating apoptosis in renal IR injury, aggravated by hyperbilirubinemia. 3-MA or PINK1-shRNA-AAV9 treatment decreased the area of collagen and proteins related to fibrosis in renal IR injury, aggravated by hyperbilirubinemia. Conclusions: We have demonstrated that hyperbilirubinemia aggravated oxidative stress, apoptosis, mitochondrial damage, and fibrosis in renal IR injury by exacerbating PINK1-PARKIN-mediated mitophagy.